1. Field of the Invention
This invention relates to transistors and more specifically to transistors with different threshold voltages.
2. Description of the Related Art
Some integrated circuits include transistors with different threshold voltages. In one example, an integrated circuit includes different regions with the transistors of one region having a threshold voltage that is different from the threshold voltages of transistors of another region. In one example, the wells of the different transistor regions have different impurity dopant concentrations to provide the transistors with different threshold voltages. Separate well masks and separate ion implanting operations are used for each region to provide wells of different doping concentrations.
The use of the same reference symbols in different drawings indicates identical items unless otherwise noted. The Figures are not necessarily drawn to scale.